Conventionally, a printing apparatus designed to print using an ultraviolet (UV) ink which is cured by illumination with UV light is known. This printing apparatus discharges an ink onto a medium from nozzles of heads, and then illuminates UV light onto dots formed on the medium. By the illumination with UV light, the dots are cured and settled down on the medium, thereby achieving good printing on a medium that cannot absorb a liquid. This printing apparatus is described in, for example, Patent Literature 1.
Patent Literature 1 discloses a printing apparatus comprising a transport unit to transport a printing medium, six heads arranged in the transportation direction to respectively discharge color inks of cyan, magenta, yellow, black, orange, and green, six illumination units for pre-curing arranged between each head on the downstream side in the transportation direction to pre-cure (peening) the dot inks discharged onto the printing medium from each head, and an illumination unit for curing to cure the dot inks which are settled down on the printing medium. The printing apparatus described in Patent Literature 1 cures the dot inks through two steps, pre-curing and curing, to prevent any blur between color inks or dot spreads.
The illumination units for pre-curing described in Patent Literature 1 are a so-called UV light illumination apparatus disposed above the printing medium to illuminate UV light onto the printing medium, and illuminate UV light in line shape along the widthwise direction of the printing medium. By the request for lightweight and compact design of the printing apparatus itself, the illumination units for pre-curing use a light emitting diode (LED) as a light source, and a plurality of LEDs is arranged along the widthwise direction of the printing medium.